The ribonucleases of human pancreas have been less completely characterized than similar enzymes of other organisms. This project is concerned with the isolation and biochemical characterization of human pancreatic ribonucleases, and in definition of the relationship between the human pancreatic enzyme and ribonucleases found in other human tissues, in serum, and in urine. In addition to enzyme characterization, a radioimmunoassay procedure will be developed to quantitate the pancreatic protein in various tissues, and to estimate cross-reactivity of structurally related RNases in other organs and organisms. Radioimmunoassay procedures will also be used to quantitate nuclease of pancreatic origin in serum of individuals suffering from a variety of diseases, particularly pancreatic carcinoma; this could permit development of a technique for early diagnosis of this malignancy.